cant install XP pro

[windows dummy]

xp pro complains that I have a firewall installed. I
uninstalled it once and I can't find it. It is still there
somewhere but I don't know how to find it.

How do you find a program running on your computer if it
has been uninstalled and all the directories have been
deleted?

Thanks,
wd

 

[windows dummy]

Nevermind, I found the answer in a search which I should
have done first.